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PCB Forum KiCAD 8: alternative pin functions
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Related

KiCAD 8: alternative pin functions

Jan Cumps
Jan Cumps over 1 year ago

I tried KiCAD's (not so) new alternative pin functions option in  the library editor.

I'm designing a project with a Renesas controller. There wasn't a symbol yet, so I started to create one. The majority of the mcu's pins have more than 5 functions. I figured this would be a good candidate to test the new option.

image

Here's the definition in the editor:

image

And a schematic with 3 symbols placed, with a few pins showing different functions.

image

I've attached the symbols: MCU_RENESAS_R_20240323_3.zip

It's a bit of work to get this set up, but it works well. Thoughts?

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  • shabaz
    shabaz over 1 year ago +4
    Very interesting! For sure it will simplify many circuit layouts. I'm looking forward to using it. I have not used that so far, but I think I would be super-tempted during symbol creation, to add one…
  • Jan Cumps
    Jan Cumps over 1 year ago in reply to shabaz +2
    I was tempted to do that for a few pins. The same that have multiple functions in the datasheet (43, 44, 47, 48) But what choice do you make as a symbol designer. It 'll always be the wrong one.…
  • Jan Cumps
    Jan Cumps over 1 year ago in reply to shabaz +2
    ... and I've also been playing with alternatives. Below a functionally-split-up one, and two with all in one symbol the U1 has a separate block for analogue, digital and power.
Parents
  • shabaz
    shabaz over 1 year ago

    Very interesting! For sure it will simplify many circuit layouts. I'm looking forward to using it.

    I have not used that so far, but I think I would be super-tempted during symbol creation, to add one more alternative pin function, which would be the names of a few of the alternate pin functions (not all)  combined with '/' separators, simply because initially one might not have decided during the first part of schematic entry, which of the alternatives they would be using.

    In other words, the user might want a pin displayed as "PD5/TIMR1/SCL" until they have later refined the selection.

    In the past, what I've done during symbol creation for microcontrollers, is to create function names of a few of the most interesting alternative pin functions, but not all of them. 

    Example:

    image

    image

    Having said that, for each project sometimes the symbols need tweaking too, e.g. to move some of the pins around, or to reduce the size of the symbol etc, since some alternative function names are long, or to change from "bidirectional" to "input", etc. (EDIT: just saw that the alternative pin functions do have that direction property alongside them - perfect).

    But this new feature is really excellent, it will make life a lot simpler.

    Also, a bit unrelated, but touching on the direction thing..

    Maybe this is unorthodox, but I took to creating an arrow symbol, and sometimes add it to schematics to remind myself of the direction of a few interesting signals. I know it shouldn't really be necessary, but might be a handy thing for occasional use, to go along with general annotation, etc.

    image

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  • Jan Cumps
    Jan Cumps over 1 year ago in reply to shabaz

    ... and I've also been playing with alternatives. Below a functionally-split-up one, and two with all in one symbol

    image

    the U1 has a separate block for analogue, digital and power.

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  • Jan Cumps
    Jan Cumps over 1 year ago in reply to shabaz

    ... and I've also been playing with alternatives. Below a functionally-split-up one, and two with all in one symbol

    image

    the U1 has a separate block for analogue, digital and power.

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  • Jan Cumps
    Jan Cumps over 1 year ago in reply to Jan Cumps

    Renesas' own house style:

    image

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  • shabaz
    shabaz over 1 year ago in reply to Jan Cumps

    Hehe yeah their's is for sure ugly. Rarely the pin-number-sequence layout can be fine. Might be ok for serving double-duty, (1) showing the chip overview and (2) showing a basic example circuit, which I suppose is what they are doing, so it's kind-of acceptable for their documentation use-case.

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  • Jan Cumps
    Jan Cumps over 1 year ago in reply to shabaz
    shabaz said:
    (2) showing a basic example circuit,

    It's for a full design:

    image

    I like what they do for their basic examples and "principles" schematics:

    image

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